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裂缝性气藏因储层中存在不同尺度的天然裂缝,总体表现为较强的非均质性。传统描述裂缝性气藏的双重介质及其扩展模型对于气藏等效过于理想,不能很好地解释裂缝特征参数对其试井曲线的影响。为此,根据蒙特卡罗法随机裂缝产生方法和非结构Voronoi网格数值生成方法产生气藏含有大尺度裂缝的离散裂缝网格模型,进一步采用控制体有限差分法建立对应的数学模型并利用全隐式法求解。最后在实例证明离散裂缝网络模型试井曲线正确性基础上,讨论并分析了大尺度裂缝特征参数(数量、角度、长度)对试井曲线的影响。研究结果表明:裂缝特征参数主要影响压力导数后期的曲线;裂缝数量越多,后期压力导数曲线下降幅度越大;裂缝长度越长,则压力导数曲线下降出现的时间越早,且下降幅度越大;裂缝角度对试井曲线特征总体影响不大,但当裂缝角度与井径向网格方向基本一致时,压力导数曲线下降出现时间最早,且下降幅度最大。
The fractured gas reservoirs generally show strong heterogeneity due to the existence of natural fractures with different scales in the reservoir. Traditionally, the dual medium and its extended model describing fractured gas reservoirs are too ideal for gas reservoirs, which can not well explain the influence of fracture parameters on their well testing curves. Therefore, according to Monte Carlo method and unstructured Voronoi mesh generation method, a discrete crack mesh model with large-scale fractures in gas reservoirs is generated, and the corresponding finite element method is used to establish the corresponding mathematical model. Implicit method to solve. Finally, on the basis of an example showing the correctness of the well testing curve of the discrete fracture network model, the influence of large scale fracture parameters (number, angle and length) on well testing curve is discussed and analyzed. The results show that the fracture characteristic parameters mainly affect the curve of the late stage of pressure derivative. The larger the number of fractures, the larger the decline of the post-pressure derivative curve. The longer the crack length, the earlier the pressure derivative curve appears, and the larger the decline is The crack angle has little effect on the well test curve characteristics. However, when the crack angle is basically the same with the radial grid direction, the pressure derivative curve appears the earliest decline and the largest decrease.